Tags:
view all tags
---+ n_s constraints from 30m telescope ---++ Background Questions to be answered: <br> * If we have a 30m telescope geared with a polarization sensitive receiver at Advanced ACTPol sensitivity (7-8 uK-arcmin at 90/150GHz, from arXiv: 1510.02809), we can measure really high ell E-modes. Does that improve the constraints on n_s? Big picture: <br> * For the Starobinsky model (R^2 inflation) on fig. 12 of the Planck 2015 Constraints on Inflation paper (arXiv: 1502.0211), aside from further constraining r, tightening the n_s constraint will be more effective in ruling it out in the near future before constraints on r gets below 1e-3. * So the question is, how quickly would measuring more high ell E-modes tighten the constraint on n_s? ---++ Current constraints on n_s From Planck's 2015 XIII. Cosmological parameters (arXiv: 1502.01589), XI. CMB power spectra, likelihoods, and robustness of parameters (arXiv: 1507.02704), and Planck's 2013 XVI Cosmological parameters paper ((arXiv: 1303.5076), the basic 6-parameter LCDM constraints are: | *parameter* | *Planck TT + lowP* | *Planck TT+TE+EE+lowP* | *Planck TT only (2013) * | | ombh2 | 0.02222 ± 0.00023 | 0.02225 ± 0.00016 | 0.02207 ± 0.00033 | | omch2 | 0.1197 ± 0.0022 | 0.1198 ± 0.0015 | 0.1196 ± 0.0031 | | 100theta | 1.04085 ± 0.00047 | 1.04077 ± 0.00032 | 1.04132 ± 0.00068 | | tau | 0.078 ± 0.019 | 0.079 ± 0.017 | 0.097 ± 0.038 | | ln(1e10 A_s) | 3.089 ± 0.036 | 3.094 ± 0.034 | 3.103 ± 0.072 | | n_s | 0.9655 ± 0.0062 | 0.9645 ± 0.0049 | 0.9616 ± 0.0094 | |||| | H_0 | 67.31 ± 0.96 | 67.27 ± 0.66 | 67.4 ± 1.4 | I added the row for H_0 because I use H_0 instead of 100*theta in my fisher code. ---++ Cosmology and Inputs for the forecast *fiducial cosmology*: <br> The fiducial cosmology I use in this forecast based on the LCDM best fit from Planck's 2013 XVI cosmological parameter (arXiv: 1303.5076) as listed in the last column in the previous section. In addition, I assume a minimal neutrino mass of ~60meV (and r = 0) *Inputs for the 30m telescope:* <br> * Beam = 0.33' ( 1 deg is about ell~200, lmax*0.33 = 200*60, lmax~36000) * Polarization noise (T noise is 1/sqrt(2) of this): 1, 3, 7.5, 10 uK-arcmin * lmaxEE = 4000, 10000, 20000; stepping through to see how much of a difference lmax makes * fsky = 0.0125, 0.125, 0.5; 0.0125 is 500 sq deg. * lmaxTT = 3000; any higher is contaminated by foregrounds * lmin various with fsky * use only the TT, TE, and EE lensed spectra -- not using phi (C^dd) *Planck prior inputs:* <br> * For the fsky = 500 sq deg, sample variance degrades the constraints by a significant amount, it is essential to have some large area survey prior (e.g. Planck) * We take the lower foreground freqs (100, 143, 217 GHz) * noise (T) = [6.8,6.0,13.1] uK-arcmin * noise (P) = [10.9,11.4,26.7] uK-arcmin * beam = [ 9.5,7.1,5.0] arcmin * lmax = 2500 * lmin = 30 * fsky = I tweak the fsky input so that the TT only constraints match the 2013 parameter constraints and the TT/TE/EE constraints match the 2015 parameter constraints to within about 10%; and fsky = 0.12 ---++ sigma(n_s) vs fsky using lensed TT/TE/EE (no delensing) <img src="%ATTACHURLPATH%/ns_vs_fsky.png" alt="ns_vs_fsky.png" width=60% /> * the solid lines are without Planck priors; the points at fsky=0.0125 has Planck prior * practically no difference going from ell=4000 to ell=20000. Perhaps expected given how smooth the peaks are beyond the 9th peak at ell~3000 (see e.g. fig 5 of SPTpol 100 sq deg EE spectrum paper arXiv: 1411.1042) * Also, sensitivity isn't a big driver. A 10uK-arcmin experiment is almost as good as a 1uK-arcmin experiment. Also expected because E-modes are much brighter. * The improvement of adding high ell EE over the Planck prior for the fsky=0.0125 case is about 7% | parameter | Planck prior alone (TT+TE+EE) | Planck + 10uK-am, lmax=4000 | Planck + 10uK-am, lmax=10000 | | sigma(n_s) | 0.0051 | 0.00474 | 0.00474 | Next: one would expect that the peaks to be sharper in its unlensed (de-lensed) state. So perhaps one can extract more information/tighter constraints on n_s after delensing the E-modes. The ideal case would be fully delensed T and E-modes, i.e. with unlensed TT, TE, and EE. This will be the best case scenario on n_s constraint given CMB TT/TE/EE spectra. ---++ sigma(n_s) vs fsky using unlensed TT/TE/EE ---++ References * Starobinsky model: * [[https://ncatlab.org/nlab/show/Starobinsky+model+of+cosmic+inflation][nLab: Starobinsky model of cosmic inflation]] * [[http://indico.ipmu.jp/indico/getFile.py/access?contribId=16&sessionId=7&resId=0&materialId=slides&confId=28][Sergei Ketov, PLANCK mission, Starobinsky inflation and its realization in old-minimal supergravity]] * [[http://arxiv.org/pdf/1402.0526v2.pdf][Linde, Inflationary Cosmology after Planck 2013?]] -- %USERSIG{KimmyWu - 2016-01-21}%
Attachments
Attachments
Topic attachments
I
Attachment
History
Action
Size
Date
Who
Comment
png
ns_vs_fsky.png
r1
manage
59.5 K
2016-01-21 - 11:57
KimmyWu
Edit
|
Attach
|
Watch
|
P
rint version
|
H
istory
:
r2
<
r1
|
B
acklinks
|
V
iew topic
|
Raw edit
|
More topic actions...
Topic revision: r1 - 2016-01-21
-
KimmyWu
Home
Site map
Main web
Sandbox web
TWiki web
Sandbox Web
Create New Topic
Index
Search
Changes
Notifications
RSS Feed
Statistics
Preferences
P
P
P
View
Raw View
Print version
Find backlinks
History
More topic actions
Edit
Raw edit
Attach file or image
Edit topic preference settings
Set new parent
More topic actions
Account
Log In
Register User
Edit
Attach
Copyright © 2008-2024 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki?
Send feedback